Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Relationship between the emergence of pertussis toxin promoter 3 (ptxP3) strains and the epidemiology of pertussis in the Netherlands, 1989–2004. A) Temporal trends in the frequencies of ptxP3 strains and notifications. In this period 99% of the strains harbored either ptxP1 or ptxP3. B) Shift in age-specific distribution of notifications.
